I have the mm675 18" flip-over handle model. But it seems to have similar workings. One day it just stopped running. I unscrewed the motor cover and noticed that a red wire had burned through where it plugged into an AC terminal on the bridge rectifier atop the motor. I re-attached and it ran OK for awhile, but soon stopped again. This time the terminal on the bridge rectifier to which the wire was attached had broken near its base. I replaced it with a new rectifier (#72256-03) from B&D, The mower ran for awhile, but soon stopped again. Yep, the same terminal on the new rectifier had broken in the same place. By this time, I began to suspect that the real culprit might be a dirty commutator (the copper surface at the top of the motor that the brushes rub against) -- it was black. So polished it to reveal the underlying bright copper with 600 grit sand paper. By then, I'd also determined that Radio Shack sells the same rectifier (RS #276-1185) for a just few dollars (B&D charges about $12.). So far, the mower's running fine. Hopefully, it's fixed. Case closed?

I question if Radio Shack #276-1185 is robust enough. That is only rated for 50 volts. I would recommend getting a part rated for at least twice the 120 volt input. On eBay, I found a rectifier # KBPC5010 rated for 1000 volts and 50 amps for only $2 if you don't mind waiting for shipment from Hong Kong. I ordered a couple of these to try out.

Www.ereplacemnetparts.com , www.toolpartsdirect.com & www.dewaltservicenet.com .price & cost listed .they deliver it for you.